The CDC had documented more than 17,600 infections as of Oct. 5—more than four times those recorded at this time last year.

When it progresses into severe disease, pertussis causes violent coughing fits punctuated by a distinct whooping sound caused by inhaling forcefully to try to catch a breath. The coughs between the whoops are brutal, Muñoz says. “They’re unstoppable,” she says. “It’s so forceful that you can actually vomit.”

A couple of contagious viruses are infecting more people in Minnesota than they have in years. Whooping cough and measles are spreading, and hospitals are on alert.

Pennsylvania has seen more cases of whooping cough than any other state this year, with 2,165 cases of the serious bacterial infection reported as of late September. At this time in 2023, the state had reported 205 cases to the Centers for Disease Control and Prevention.